Central Processing Units (CPU) in various environments are facing constantly increasing power constraints. In many cases power is becoming the major performance limiter. For example, reducing CPU performance in order to remain within the cooling limits. Some exemplary usage models that rely on the ability to monitor the CPU's energy/power consumption in order to improve the CPU's/system's performance in a thermally limited environment are listed hereinafter:    1. Power aware scheduling usage module that identifies “hot threads” in CPUs/Cores and balances the thermal load between CPUs/Cores in multi CPU/core environment;    2. A usage module that optimizes the performance of high power applications in a thermally constrained environment by “smoothing” their power profile; and    3. A usage module that uses power driven thermal controls of the CPU (replacing the non-deterministic temperature driven controls) for CPU and/or platform management.
Other usage modules and/or methods may employ power measurement by adding system components that are dedicated for this purpose. These methods may add to the CPU system complexity and to the overall costs of the CPU semiconductors devices. Furthermore, these methods do not provide the required functionality of cost effective energy/power control of the CPU cores.
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